public class T {
    public static void main(String[] args) {
        MySingList list=new MySingList();
        list.addFirst(1);
        list.addLast(2);
        list.addLast(3);
        list.addLast(3);
        list.display();
        list.removeAllKey(3);
        list.display();
        System.out.println(list.contains(1));
    }
}
